ICES Report Measures Chronic Complications of Diabetes

391

Diabetes is a serious and growing health problem affecting over six per cent of Ontarians. While diabetes is often thought of as a blood sugar problem, it is the serious and long-term complications of diabetes that have the greatest impact on the lives of people affected by it, and on the health system as a whole. Diabetes is a leading cause of cardiovascular disease, blindness, kidney failure leading to dialysis, and amputation.

Researchers at the Institute for Clinical Evaluative Sciences (ICES) have conducted a series of studies to measure the impact of diabetes and its associated complications. Diabetes in Ontario: An ICES Practice Atlas is a three-part report that describes trends in diabetes over time and across the province, the short-term (acute) and long-term (chronic) complications of the disease, and how it impacts special populations. The second part of the Atlas, Module 2, was released in December 2002 and focuses on rates of chronic complications such as heart and kidney disease.

The goal of this ICES research was to develop a province-wide picture of diabetes. In order to achieve this, researchers could not simply study samples of patients in a few locations. Instead, hospitalization records and physicians’ billing records for the entire province were used. This allowed for rates of heart and kidney disease in people with and without diabetes to be examined, at both provincial and regional levels.

Heart DiseaseIn Ontario, about 20,000 people are admitted to hospitals due to heart attacks. Although people with diabetes make up only six percent of the population, they experienced more than 30 per cent of all heart attacks. Hospital admission rates for heart attacks were up to three times higher in people with diabetes. People with diabetes not only experienced more heart disease, they had it at an earlier age – heart attack rates among people with diabetes were comparable the rates seen in those without diabetes that were 15 to 20 years older. Those with diabetes also tended to have poorer outcomes following heart attacks, longer hospital stays, a greater chance of being readmitted to hospital, and a higher proportion of deaths.

While these results show the heavy impact of heart disease in people with diabetes, there were some positive findings. Trends over time suggested improvements in care are leading to better outcomes for people with diabetes. Hospital admission rates for heart attacks fell by nearly 10 per cent among people with diabetes between 1995 and 1999.

Kidney Disease and DialysisKidney failure is a particularly serious complication of diabetes. Patients whose kidneys have failed require either dialysis or a kidney transplant to survive. For most people, dialysis requires treatment in hospital three times per week.

While people without diabetes may suffer kidney failure, those with diabetes are at much greater risk. In Ontario, dialysis rates were found to be 12 times higher in people with diabetes versus those without the condition. The number of people with diabetes starting chronic dialysis is growing eight times faster than in the non-diabetic population. (Figure). The largest degree of growth occurred in people over age 75, resulting in a dialysis population that is older and has a greater number of chronic diseases.

Study ImplicationsThese findings confirm the heavy burden of heart and kidney complications faced by people with diabetes, and highlight the need for in-hospital, satellite and in-home dialysis services. In addition, not only were rates of heart disease high, but persons with diabetes also tended to experience these complications at much younger ages.

Earlier work reported in Module 1 of the Atlas showed a 31 per cent increase in the rate of diabetes between 1995 and 1999 in Ontario. This rise in the total number of Ontarians with the condition, together with rising rates of obesity and the aging population, means that many more people are at risk for diabetes complications.

Trends in these diabetes complications over time appear to tell a conflicting story. As care for diabetes improves, the risk of an individual patient developing a complication decreases. This improvement is reflected, for instance, in the 10 per cent fall in heart attack rates over five years. However, at the same time, the number of people with diabetes is rapidly growing. That growth in the diabetes population is outstripping the improvements in outcomes for individual patients. As a result, the number of people with diabetes having a heart attack grew by 25 per cent over the same study period of 1995 to 1999.

Response to these findings needs to come from many fronts. Governments, health planners and providers will need to ensure that health care resources are available to serve a growing number of diabetes patients requiring specialty services. People with diabetes and their health-care providers need to work together to prevent complications. Many new therapies are available to reduce the risk of heart and kidney disease, as well as other diabetes complications, but not all patients are receiving these treatments. Finally, public health programs will be needed to address diabetes risk factors and prevention.